Differential effects of flumazenil in alcoholic and nonalcoholic cirrhotic patients

Simultaneously Predicting the Pharmacokinetics of CES1-Metabolized Drugs and Their Metabolites Using Physiologically Based Pharmacokinetic Model in Cirrhosis Subjects

Hepatic carboxylesterase 1 (CES1) metabolizes numerous prodrugs into active ingredients or direct-acting drugs into inactive metabolites. We aimed to develop a semi-physiologically based pharmacokinetic (semi-PBPK) model to simultaneously predict the pharmacokinetics of CES1 substrates and their active metabolites in liver cirrhosis (LC) patients. Six prodrugs (enalapril, benazepril, cilazapril, temocapril, perindopril and oseltamivir) and three direct-acting drugs (flumazenil, pethidine and remimazolam) were selected. Parameters such as organ blood flows, plasma-binding protein concentrations, functional liver volume, hepatic enzymatic activity, glomerular filtration rate (GFR) and gastrointestinal transit rate were integrated into the simulation. The pharmacokinetic profiles of these drugs and their active metabolites were simulated for 1000 virtual individuals. The developed semi-PBPK model, after validation in healthy individuals, was extrapolated to LC patients. Most of the observations fell within the 5th and 95th percentiles of simulations from 1000 virtual patients. The estimated AUC and Cmax were within 0.5-2-fold of the observed values. The sensitivity analysis showed that the decreased plasma exposure of active metabolites due to the decreased CES1 was partly attenuated by the decreased GFR. Conclusion: The developed PBPK model successfully predicted the pharmacokinetics of CES1 substrates and their metabolites in healthy individuals and LC patients, facilitating tailored dosing of CES1 substrates in LC patients.

Flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy is a common complication of cirrhosis which results in poor brain functioning. The spectrum of changes associated with hepatic encephalopathy ranges from the clinically 'indiscernible' or minimal hepatic encephalopathy to the clinically 'obvious' or overt hepatic encephalopathy. Flumazenil is a synthetic benzodiazepine antagonist with high affinity for the central benzodiazepine recognition site. Flumazenil may benefit people with hepatic encephalopathy through an indirect negative allosteric modulatory effect on gamma-aminobutyric acid receptor function. The previous version of this review, which included 13 randomised clinical trials, found no effect of flumazenil on all-cause mortality, based on an analysis of 10 randomised clinical trials, but found a beneficial effect on hepatic encephalopathy, based on an analysis of eight randomised clinical trials.

OBJECTIVES

To evaluate the beneficial and harmful effects of flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, and LILACS; meeting and conference proceedings; and bibliographies in May 2017.

SELECTION CRITERIA

We included randomised clinical trials regardless of publication status, blinding, or language in the analyses of benefits and harms, and observational studies in the assessment of harms.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We undertook meta-analyses and presented results using risk ratios (RR) with 95% confidence intervals (CI) and I2 values as a marker of heterogeneity. We assessed bias control using the Cochrane Hepato-Biliary Group domains; determined the quality of the evidence using GRADE; evaluated the risk of small-study effects in regression analyses; and conducted trial sequential, subgroup, and sensitivity analyses.

MAIN RESULTS

We identified 14 eligible randomised clinical trials with 867 participants, the majority of whom had an acute episode of overt hepatic encephalopathy. In addition, we identified one ongoing randomised clinical trial. We were unable to gather outcome data from two randomised clinical trials with 25 participants. Thus, our analyses include 842 participants from 12 randomised clinical trials comparing flumazenil versus placebo. We classified one randomised clinical trial at low risk of bias in the overall assessment and the remaining randomised clinical trials at high risk of bias. The duration of follow-up ranged from a few minutes to two weeks, but it was less than one day in the majority of the trials.In total, 32/433 (7.4%) participants allocated to flumazenil versus 38/409 (9.3%) participants allocated to placebo died (RR 0.75, 95% CI 0.48 to 1.16; 11 randomised clinical trials; low quality evidence). The Trial Sequential Analysis and the one randomised clinical trial assessed as low risk of bias (RR 0.76, 95% CI 0.37 to 1.53) found no beneficial or harmful effects of flumazenil on all-cause mortality. The methods used to evaluate hepatic encephalopathy included several different clinical scales, electrophysiological variables, and psychometric tests. Flumazenil was associated with a beneficial effect on hepatic encephalopathy when including all randomised clinical trials (RR 0.75, 95% CI 0.71 to 0.80; 824 participants; nine randomised clinical trials; low quality evidence), or just the trial at low risk of bias (RR 0.78, 95% CI 0.72 to 0.84; 527 participants). The Trial Sequential Analysis supported a beneficial effect of flumazenil on hepatic encephalopathy. The randomised clinical trials included little information about causes of death and little information on non-fatal serious adverse events.

AUTHORS' CONCLUSIONS

We found low quality evidence suggesting a short-term beneficial effect of flumazenil on hepatic encephalopathy in people with cirrhosis, but no evidence of an effect on all-cause mortality. Additional evidence from large, high quality randomised clinical trials is needed to evaluate the potential benefits and harms of flumazenil in people with cirrhosis and hepatic encephalopathy.

Flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy is a common complication of cirrhosis which results in poor brain functioning. The spectrum of changes associated with hepatic encephalopathy ranges from the clinically 'indiscernible' or minimal hepatic encephalopathy to the clinically 'obvious' or overt hepatic encephalopathy. Flumazenil is a synthetic benzodiazepine antagonist with high affinity for the central benzodiazepine recognition site. Flumazenil may benefit people with hepatic encephalopathy through an indirect negative allosteric modulatory effect on gamma-aminobutyric acid receptor function. The previous version of this review, which included 13 randomised clinical trials, found no effect of flumazenil on all-cause mortality, based on an analysis of 10 randomised clinical trials, but found a beneficial effect on hepatic encephalopathy, based on an analysis of eight randomised clinical trials.

OBJECTIVES

To evaluate the beneficial and harmful effects of flumazenil versus placebo or no intervention for people with cirrhosis and hepatic encephalopathy.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, and LILACS; meeting and conference proceedings; and bibliographies in May 2017.

SELECTION CRITERIA

We included randomised clinical trials regardless of publication status, blinding, or language in the analyses of benefits and harms, and observational studies in the assessment of harms.

DATA COLLECTION AND ANALYSIS

Two review authors extracted data independently. We undertook meta-analyses and presented results using risk ratios (RR) with 95% confidence intervals (CI) and I2 values as a marker of heterogeneity. We assessed bias control using the Cochrane Hepato-Biliary Group domains; determined the quality of the evidence using GRADE; evaluated the risk of small-study effects in regression analyses; and conducted trial sequential, subgroup, and sensitivity analyses.

MAIN RESULTS

We identified 14 eligible randomised clinical trials with 867 participants, the majority of whom had an acute episode of overt hepatic encephalopathy. In addition, we identified one ongoing randomised clinical trial. We were unable to gather outcome data from 2 randomised clinical trials with 25 participants. Thus, our analyses include 842 participants from 12 randomised clinical trials comparing flumazenil versus placebo. We classified one randomised clinical trial at low risk of bias in the overall assessment and the remaining randomised clinical trials at high risk of bias. The duration of follow-up ranged from a few minutes to two weeks, but it was less than one day in the majority of the trials.In total, 32/433 (7.4%) participants allocated to flumazenil versus 38/409 (9.3%) participants allocated to placebo died (RR 0.75, 95% CI 0.48 to 1.16; 11 randomised clinical trials; low quality evidence). The Trial Sequential Analysis and the one randomised clinical trial assessed as low risk of bias (RR 0.76, 95% CI 0.37 to 1.53) found no beneficial or harmful effects of flumazenil on all-cause mortality. The methods used to evaluate hepatic encephalopathy included several different clinical scales, electrophysiological variables, and psychometric tests. Flumazenil was associated with a beneficial effect on hepatic encephalopathy when including all randomised clinical trials (RR 0.75, 95% CI 0.71 to 0.80; 824 participants; 9 randomised clinical trials; low quality evidence), or just the trial at low risk of bias (RR 0.78, 95% CI 0.72 to 0.84; 527 participants). The Trial Sequential Analysis supported a beneficial effect of flumazenil on hepatic encephalopathy. The randomised clinical trials included little information about causes of death and little information on non-fatal serious adverse events.

AUTHORS' CONCLUSIONS

We found low quality evidence suggesting a short-term beneficial effect of flumazenil on hepatic encephalopathy in people with cirrhosis, but no evidence of an effect on all-cause mortality. Additional evidence from large, high quality randomised clinical trials is needed to evaluate the potential benefits and harms of flumazenil in people with cirrhosis and hepatic encephalopathy.

Neurocognitive performance, alcohol withdrawal, and effects of a combination of flumazenil and gabapentin in alcohol dependence

BACKGROUND

Among some alcohol-dependent individuals, early alcohol abstinence is marked by alcohol withdrawal (AW), a phenomenon mediated by GABA and glutamate signaling. We previously reported that a combination of 2 medications that affect GABA and glutamate tone, gabapentin and flumazenil, more effectively reduced drinking among individuals with higher pretreatment AW (Anton et al., 2009). This study evaluated whether this finding is related to changes in neurocognitive performance, which is also affected by cortical GABA and glutamate tone.

METHODS

Neurocognitive performance was assessed at baseline and twice during the first week of treatment among 60 alcohol-dependent participants in the previously published clinical trial.

RESULTS

AW was associated with poorer baseline performance on 4 of 8 measures, and individuals with higher baseline AW who received the gabapentin and flumazenil combination demonstrated greater improvement on a measure of response inhibition than those with lower AW or those who received a combination of placebos. Improvement in response inhibition during the first week and medication group interacted in their effect on subsequent drinking, such that improvement predicted greater abstinence only among individuals who received gabapentin and flumazenil. Improvement on other neurocognitive measures was neither differentially impacted by medication or baseline AW nor related to subsequent drinking.

CONCLUSIONS

Taken together, these data suggest that acute AW accounts for a small proportion of variance in neurocognitive performance, that gabapentin and flumazenil slightly improve response inhibition during early abstinence, and that such improvement may somewhat reduce later drinking. However, these medications may not affect other neurocognitive domains.

Benzodiazepine receptor antagonists for hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy may be associated with accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition. Benzodiazepine receptor antagonists may have a beneficial effect on patients with hepatic encephalopathy.

OBJECTIVES

To evaluate the beneficial and harmful effects of benzodiazepine receptor antagonists for patients with hepatic encephalopathy.

SEARCH STRATEGY

Eligible trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Controlled Trials Register on The Cochrane Library, MEDLINE and EMBASE (last search: January 2004), reference lists of relevant articles, authors of trials, and pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing any benzodiazepine receptor antagonist versus placebo or no intervention for hepatic encephalopathy.

DATA COLLECTION AND ANALYSIS

Two reviewers independently included trials and extracted data. Binary outcomes are reported as risk difference (RD) with 95% confidence intervals (CI) based on a random effects model. Statistical heterogeneity was explored by a chi-squared test with significance set at P < 0.1. The inconsistency across trials was assessed by I(2). Potential sources of heterogeneity were explored through subgroup analyses.

MAIN RESULTS

Thirteen randomised trials with 805 patients were included. Eight trials used a crossover design. All trials were double-blind and assessed flumazenil versus placebo. Data on all outcomes could not be extracted from all trials. The included patients had a favourable prognosis (361/390 [93%] survived in the flumazenil group versus 345/376 [92%] in the placebo group). Flumazenil had a significant beneficial effect on improvement of hepatic encephalopathy at the end of treatment (RD 0.28; 95% CI 0.20 to 0.37, eight trials). Flumazenil had no significant effect on recovery (RD 0.13; 95% CI -0.09 to 0.36, two trials) or mortality RD 0.01; 95% CI -0.05 to 0.07, 10 trials). Flumazenil may be associated with adverse events, but trial results were heterogeneous.

REVIEWERS' CONCLUSIONS

Flumazenil had a significant beneficial effect on short-term improvement of hepatic encephalopathy in patients with cirrhosis and a highly favourable prognosis. Flumazenil had no significant effect on recovery or survival. Considering the fluctuating nature of hepatic encephalopathy, future trials should use a parallel design and assess if treatment with flumazenil leads to a sustained improvement or increased recovery and survival. Until this has been demonstrated, flumazenil may be considered for patients with chronic liver disease and hepatic encephalopathy, but cannot be recommended for routine clinical use.

Benzodiazepine receptor antagonists for acute and chronic hepatic encephalopathy

BACKGROUND

The pathogenesis of hepatic encephalopathy is unknown. It has been suggested that liver failure leads to the accumulation of substances that bind to a receptor-complex in the brain resulting in neural inhibition which may progress to coma. Several trials have assessed benzodiazepine receptor antagonists for hepatic encephalopathy, but the results are conflicting.

OBJECTIVES

To evaluate the efficacy and safety of benzodiazepine receptor antagonists for patients with acute or chronic hepatic encephalopathy.

SEARCH STRATEGY

Eligible trials were identified through The Cochrane Hepato-Biliary Group Controlled Trials Register, The Cochrane Controlled Trials Register, MEDLINE, EMBASE, reference lists of relevant articles, authors of trials, and the pharmaceutical company known to produce benzodiazepine receptor antagonists.

SELECTION CRITERIA

Randomised trials comparing any benzodiazepine receptor antagonist versus placebo or no intervention for hepatic encephalopathy were included, regardless of language or publication status.

DATA COLLECTION AND ANALYSIS

Trial inclusion and data extraction were made independently by two contributors. Depending on the presence or absence of significant heterogeneity (P<0.1) a random or fixed effect model was used. Potential causes for heterogeneity were explored by sensitivity analyses.

MAIN RESULTS

Twelve randomised trials with 765 patients were included. Eight trials used a crossover design. All trials were double-blind and assessed flumazenil versus placebo. Data on all outcomes could not be extracted from all trials. The included patients had a favourable prognosis (341/370 (92%) survived in the flumazenil group versus 325/356 (91%) in the placebo group). Flumazenil had no significant effect on full recovery (two trials), survival (nine trials), or on the occurrence of adverse events (five trials). However, flumazenil was associated with a significant effect on improvement of hepatic encephalopathy compared to placebo at the end of treatment (103/346 (30%) versus 23/332 (7 %), risk difference 0.23, 95% confidence interval 0.18 to 0.28, five trials).

REVIEWER'S CONCLUSIONS

Flumazenil had no significant effect on recovery or survival from hepatic encephalopathy. However, flumazenil had a significant effect on short-term improvement of hepatic encephalopathy in some patients with chronic liver disease and a highly favourable prognosis. Considering the fluctuating nature of hepatic encephalopathy, future trials should use a parallel design and assess if treatment with flumazenil leads to a sustained improvement or increased recovery and survival. Until this has been demonstrated, flumazenil may be considered for patients with chronic liver disease and hepatic encephalopathy, but cannot be recommended for routine clinical use.

Brain uptake of iomazenil in cirrhotic patients: a single photon emission tomography study

Brain uptake of 123I-iomazenil was studied in seven cirrhotic patients and eight normal controls using single photon emission computerized tomography. The highest concentration of the ligand was found in the occipital cortex, which corresponds to the brain region with the highest concentration of benzodiazepine receptors. The peak uptake was delayed in patients across all brain regions. The uptake in occipital cortex was higher in low albumin cirrhotics. Patients with low albumin also presented a more delayed peak uptake in occipital cortex and a higher volume of distribution of iomazenil in plasma, compared to patients with normal albumin levels and controls. The changes in brain uptake (delayed peak uptake and increased maximal uptake in occipital cortex) appears to reflect changes in the pharmacokinetics of the ligand, particularly in cirrhotics with low levels of plasma albumin. The curve of brain uptake of the tracer was modelled into a two compartments equation, which seems to provide a practical and reliable method to calculate the slopes of acquisition and decay, time to peak and maximal acquisition.

Behavioural pharmacological characteristics of honokiol, an anxiolytic agent present in extracts of Magnolia bark, evaluated by an elevated plus-maze test in mice

Honokiol, a neolignane derivative of Magnolia bark, has central depressant action and, at much lower doses, anxiolytic activity. We have investigated the characteristics of the behavioural effects of honokiol by means of an elevated plus-maze test. In the plus-maze test a single oral dose of 20 mg kg(-1) honokiol significantly prolonged the time spent in the open arms of the maze, suggesting anxiolytic effect. Moreover, when honokiol was administered daily for seven days and the plus-maze test was conducted 3 or 24 h after the last administration, significant prolongation of the time in the open arms was manifested even for doses of 0.2 mg kg(-1). The maximum effect was observed for doses of 0.5 mg kg(-1). Honokiol at any dose in both single and repeated administration schedules caused neither change in motor activity nor disruption of traction performance. Orally administered diazepam, 0.5-2 mg kg(-1), caused dose-dependent prolongation of the time spent in the open arms of the maze with a significant increase in motor activity at 1 mg kg(-1), and dose-dependent disruption of traction performance. The changes in the plus-maze performance after treatment for seven days with 0.2 mg kg(-1) honokiol and after a single treatment with 1 mg kg(-1) diazepam were almost equivalent. The effect of honokiol (0.2 mg kg(-1), treatment for seven days) was inhibited by subcutaneous flumazenil (0.3 mg kg(-1)) and (+)-bicuculline (0.1 mg kg(-1)) and by intraperitoneal CCK-4 (50 microg kg(-1)) and caffeine (30 mg kg(-1)). The anxiolytic effect of diazepam (1 mg kg(-1)) was also inhibited by flumazenil and bicuculline. However, the combined administration of diazepam with caffeine enhanced the effect, and diazepam completely reversed the effect of CCK-4. These results suggest that, in contrast with diazepam, honokiol selectively induces an anxiolytic effect with less liability of eliciting motor dysfunction and sedation or disinhibition. The combined effects of the drug also revealed that the mechanism of anxiolytic effect of honokiol is partially different from that of diazepam.

The influence of alcoholism and cirrhosis on benzodiazepine receptor function

In a previous study we reported that the affinity of the platelet benzodiazepine receptor was greater in alcoholic cirrhotic patients compared with normal controls and that there were detectable ligands for the neuronal benzodiazepine receptor in plasma from both alcoholic and nonalcoholic cirrhotic patients. The aim of the present study was to assess the separate contributions of alcoholism and cirrhosis to the presence of ligands in plasma for the neuronal and peripheral benzodiazepine receptors and to changes in peripheral benzodiazepine receptor binding in platelets. These parameters were measured in 10 alcoholic cirrhotics, 9 nonalcoholic cirrhotics, 7 alcoholics with a normal liver function, and 15 nonalcoholic subjects and normal liver function. Both groups of alcoholics had been abstinent for several months and the nonalcoholic groups had abstained for 24 h before the study. The concentration of ligands for the peripheral benzodiazepine receptor were significantly higher in both cirrhotic groups compared with the other two groups, suggesting that cirrhosis was responsible for this accumulation. Furthermore, the cirrhotic patients with detectable concentrations of these ligands had significantly poorer episodic memory than those without ligands. However, the presence of ligands for the peripheral benzodiazepine receptor did not correlate with the change in receptor affinity, which was increased in the alcoholic cirrhotic group compared with all other groups. Neither cirrhosis nor alcoholism altered the peripheral benzodiazepine receptor number. The cirrhotic patients with detectable ligands for the neuronal benzodiazepine receptor showed psychomotor slowing and executive dysfunction. The results suggest that the ligands for the peripheral benzodiazepine receptor may contribute to some of the cognitive deficits seen in hepatic encephalopathy, but are not responsible for the receptor affinity change seen in the alcoholic cirrhotics. This affinity change is not solely due to the effects of alcohol and could possibly serve as a marker for those at risk for developing alcoholic cirrhosis.

Cognitive impairments of alcoholic cirrhotic patients: correlation with endogenous benzodiazepine receptor ligands and increased affinity of platelet receptors

OBJECTIVES

To determine whether differences in cognitive function between alcoholic and non-alcoholic cirrhotic patients relate to differences in endogenous ligands for the benzodiazepine receptor and/or benzodiazepine binding.

METHODS

Seventeen grade-I hepatic encephalopathic patients (nine alcoholic, eight non-alcoholic) were compared with 10 matched controls on plasma concentrations of endogenous ligands for the neuronal benzodiazepine receptor, benzodiazepine binding in platelets, and performance on tests of cognitive function.

RESULTS

Both groups of patients were impaired on verbal recall and on reaction time tasks compared with controls; alcoholic patients were also impaired on Reitan's trails test and digit cancellation. Four of the 17 patients had detectable concentrations of endogenous benzodiazepine ligands and they were more impaired than other patients on trails and cancellation tests. The groups did not differ in the density of benzodiazepine platelet receptors, but receptor affinity was higher in alcoholic patients than in controls; furthermore, receptor affinity correlated with the time to complete the cancellation task and with reaction time.

CONCLUSION

Alcoholic cirrhotic patients may have enhanced concentrations of ligands for neuronal and peripheral benzodiazepine receptors and these may contribute to cognitive impairments in these patients.